Antibacterial and Anti-Biofilm Activities of Essential Oil Compounds against New Delhi Metallo-β-Lactamase-1-Producing Uropathogenic Klebsiella pneumoniae Strains

The World Health Organization points out that the opportunistic pathogen Klebsiella pneumoniae that causes various infections among others, urinary tract infections (UTIs), is one of the high-priority species due to a global problem of antimicrobial resistance. The aim of this study was to investigate antibacterial and anti-biofilm activities of chosen constituents of essential oils against NDM-1-producing, uropathogenic K. pneumoniae strains. The genes encoding lipopolysaccharide (uge, wabG), adhesin gene fimH (type I fimbriae) and gene encoding carbapenemase (bla(NDM-1)) for all tested strains were detected by PCR amplification. The K. pneumoniae ATCC BAA-2473 reference strain was uge- and bla(NDM-1)-positive. The effectiveness of fifteen essential oil compounds (EOCs) (linalool, β-citronellol, linalyl acetate, menthone, (−)-menthol, (+)-menthol, geraniol, eugenol, thymol, trans-anethole, farnesol, β-caryophyllene, (R)-(+)-limonene, 1,8-cineole, and carvacrol) was assessed by determining the MIC, MBC, MBC/MIC ratio against K. pneumoniae strains by the microdilution method. Anti-biofilm properties of these compounds were also investigated. Thymol, carvacrol and geraniol exhibited the best antibacterial and anti-biofilm activities against uropathogenic NDM-1-producing K. pneumoniae isolates. Results of our investigations provide a basis for more detailed studies of these phytochemicals on their application against uropathogenic K. pneumoniae.